1. Field of the Invention
The present invention relates to the field of sand screens used to complete subterranean wells and, more specifically, to devices and methods used for routing control lines with a sand screen.
2. Description of Related Art
Hydrocarbon fluids such as oil and natural gas are obtained from a subterranean geologic formation, referred to as a reservoir, by drilling a well that penetrates the hydrocarbon-bearing formation. Once a wellbore has been drilled, the well must be completed before hydrocarbons can be produced from the well. A completion involves the design, selection, and installation of equipment and materials in or around the wellbore for conveying, pumping, or controlling the production or injection of fluids. After the well has been completed, production of oil and gas can begin.
Sand or silt flowing into the wellbore from unconsolidated formations can lead to an accumulation of fill within the wellbore, reduced production rates and damage to subsurface production equipment. Migrating sand has the possibility of packing off around the subsurface production equipment, or may enter the production tubing and become carried into the production equipment. Due to its highly abrasive nature, sand contained within production streams can result in the erosion of tubing, flowlines, valves and processing equipment. The problems caused by sand production can significantly increase operational and maintenance expenses and can lead to a total loss of the well.
One means of controlling sand production is the placement of relatively large grain sand (i.e., xe2x80x9cgravelxe2x80x9d) around the exterior of a slotted, perforated, or other type liner or sand screen. The gravel serves as a filter to help assure that formation fines and sand do not migrate with the produced fluids into the wellbore. In a typical gravel pack completion, a sand screen is placed in the wellbore and positioned within the unconsolidated formation that is to be completed for production. The sand screen is typically connected to a tool that includes a production packer and a cross-over, and the tool is in turn connected to a work or production tubing string. The gravel is mixed with a carrier fluid and pumped in slurry form down the tubing and through the crossover, thereby flowing into the annulus between the sand screen and the wellbore. The carrier fluid in the slurry leaks off into the formation and/or through the sand screen. The sand screen is designed to prevent the gravel in the slurry from flowing through it and entering into the production tubing. As a result, the gravel is deposited in the annulus around the sand screen where it forms a gravel pack. It is important to size the gravel for proper containment of the formation sand, and the sand screen must be designed in a manner to prevent the flow of the gravel through the sand screen.
At times it is desired to place other items within the wellbore adjacent to the sand screen, such as alternate pathway tubes or control lines. If these items are placed outside of the sand screen, they may be damaged when they and the sand screen are inserted into the wellbore. If these items are located within the longitudinal bore of the sand screen, they may interfere with the production of fluids or the subsequent running of other downhole tools.
There is a need for improved apparatus and methods that enable the inclusion of control lines and/or alternate pathway tubes adjacent to a sand screen.
One embodiment of the invention is a sand screen comprising a shroud having a channel or passageway formed therein. The sand screen can include a restraining element adapted to maintain one or more control lines within the channel. The sand screen can also include a base pipe and a screen. The shroud can be attached to the base pipe by a connecting member and can at least partially surround the screen and define a space between them. The shroud can also be perforated. At least one alternate path can be positioned within the shroud and can be positioned within the space between the shroud and the screen.
Other features and embodiments will become apparent from the following description, the drawings, and the claims.